Note: Descriptions are shown in the official language in which they were submitted.
~224837
COMPOUND INDUCTION ELECTRIC ROTATING MACHINE
r
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention generally relates to dynamo-
electr~cmachines capable of operating in a generator mode
or in a motor mode and, more specifically, to increased
efficiency compound interaction AC andjor DC dynamo-
electric machines.
Descr ption of the Prior_Art
Most armatures have distributed windings, i.e.,
windings which are spread over a number of slots around
the periphery of a rotor or armature of the machine. In
most conventional designs the machines are of a radial
magnetic gap type so that electrical currents applied to
the windings of the rotor or stator, or to the windings of
both, generates electromagnetic fields in the rotor or in
the stator, as the case may be. The torque or the EMF
induced in the machine results from the interaction between
the magnetic field in the radial magnetic gap and the
generally parallel axial winding portions of the armature
coils disposed in the axial grooves or slots of the
armature. ~owever, the back and front connections which
are those portions of the windings which connect substan-
tially diametrically opposing axial wire portions situatedin the grooves have not been utilized in order to enhance
the efficiency of the machine. Such front and back
connections, which are substantially normal to the axis of
the machine, rotate with the armature but have not been
used to increase the torque of the machine, in the case of
a motor, or to increase the power output, in the case of a
~1r
12Z4~337
generator. Specially designed special purpose dynamo-
electric machines have been proposed in order to increase
the efficiency and power output for given weight and size
of the machine. One approach has been to use axial air gap
type machines such as the brushless axial air gap inductor-
type dynamoelectric machine disclosed in U. S. Patent No.
3,467,844. The machine disclosed in the aforementioned
patent uses plural variable reluctance rotors and a
toroidal coil stator therebetween. However, the machine
does not ma~e use of a radial air gap. Accordingly, the
machine requires a special construction which does not
make use of conventional distributed armature-type windings.
In an effort to provide electric machines which
are inexpensive and small in size, there has also been
developed disc-type rotors in machines defining axial air
gaps. One example of such a machine is disclosed in U. S.
Patent No. 3,558,947. In that patent, a D. C. motor is
described which includes a disc armature and a permanent
magnet stator providing an axial air gap. Such machines,
which use axial air gaps and generally flat armatures are
sometimes referred to as having a pancake coil. Such
pancake coils or rotors contain all of the armature turns
in a generally flat plane which is normal to the shaft or
axis of the machine. There is, accordingly, no axial air
gap as there is in conventional cylindrical rotor distri-
buted armature winding machines. In some nstances,
instead of making use of a winding on a pancake-type rotor,
a flat substrate is provided on which various winding
patterns are printed. Such winding patterns may be etched,
plated, printed or pressure bonded on such thin disc-
armature of insulating material. However, because of the
difficulties which have been experienced with such thin
disc-armatures, primarily because of the flexibility of
the discs on which the conductors are placed, an electric
35 machine has been disclosed in U. S. Patent No. 3,487,246
~2~483~
which applies such conductive pattern on a conical surface
of an insulating member. The purpose of makîng the arma-
ture conical is to provide a more rigid structure than the
flat disc armature structures. Such flat substrate
armature machines, however, whether flat or conical, cannot
provide the mechanical or electrical power output as is
possible with conventional cylindrical rotor machines.
U. S. Patent No. 4,143-,288 discloses a coreless
motor which includes a rotor having a plurality of coils
constituting a pancake coil. The motor disclosed in this
patent is a special purpose motor which is capable of being
attached to electrical parts such as balance weights,
servo-mechanisms, etc. However, this motor likewise lacks
the conventional cylindrical rotor found in most dynamo-
electric machines which is provided with a distributed
armature winding. As with the other pancake-type arma-
tures, the coreless motor disclosed in this patent does not
have a radial air gap and, therefore, does not have the
ability to compound the interaction or induction in the
machine both at the axial ends and the peripheral surface
of the armature.
There has also been proposed a dynamoelectric
machine which has plural stators. Such machines have
been disclosed in U. S. Patent Nos. 3,396,296; 3,426,224;
3,602,749; 3,729,642 and 4,114,057. These patents, all
issued to the same patentee, were intended to combine
advantages of using both the radial gap and axial gap in
dynamoelectric machines. However, to do so, applicant
disclosed a complicated structure making use of both inner
and outer stators and a hollow cylindrical rotor. In
these structures, a first stator is disclosed within the
hollow cylindrical rotor and a second stator, also cylin-
drical in shape is disposed such as to surround the rotor.
In this way, double radia] air gaps are formed. It was also
suggested that end stators may be used to form axial air
~Z2483~
-- 4
gaps between the ends of the rotor and the magnetic
field created by the end stators. These machines were
described as having greater efficiency than conventional
motors or generators as the result of the increased
interaction between the multitude of magnetic field and
electromagnetic fields. However, the machines proposed
in the last mentioned series of patents are unconventional
in design and construction, do not have radial grooves
and do not have front and back armature winding connections
at thé axial ends of the rotor as is present in the
normal distributed armature winding arrangements.
Instead, the windings are each wound around a flat,
relatively thin magnetic core.
Other special purpose dynamoelectric machines
11 have been proposed for special appliations. Thus, for
example, in U.S. Patent No. 4,051,401, a spherical
air gap motor is disclosed wherein the magnetic ring
closing the stotor magnetic loop has a non-cylindrical
shape. Such electric motors with spherical air gaps
12 have found applications in pump drives, particularly
for hermetically sealed chemical pumps.
1224837
The use of magnets at the axial ends of an
armature is also known. See, for example, U.S.
Patent No. 4,237,394. However, the last mentioned
patent utilizes the end magnets as part of a
frequency generator where the magnets are used as
part of a variable reluctance magnetic circuit to
induce a signal of a desired frequency in a generation
coil.
The prior art has not, however, utilized both
perpheral and end stators in cylindrical rotor machines
to simultaneously cooperate with both rotor axial and
radial coil portions to enhance the efficiency of the
machine and significantly improve its performance
characteristics. By harnessing the additional torque,
in the case of motor operation, or the additional
electromagnetic inductive force, in the case of generator
operation, significant improvements in efficiency can be
obtained without compromising any constructional
features and without the need to resort to unconven-
tional, complicated or costly machine designs.
Summary of the Invention
Accordingly, it is an object of the present inventionto provide a dynamoelectric machine which is not pos-
sessed of the disadvantages associated with the afore-
mentioned prior art machines.
~224837
It is another object of the present invention toprovide a dynamoelectric machine which is simple in
construction and economical to manufacture.
It is still another object of the present invention
to provide a dynamoelectric machine of the type having
a cylindrical rotor and which makes simultaneous use of
both peripheral and end stators which cooperate with
radial and axial rotor coil portions to provide compound
interaction between the armature and multiple stators.
It is yet another object of the present invention
to provide a dynamoelectric machine of the type
suggested in the last object which has a significantly
higher efficiency than the prior art comparable
machines to thereby provide substantial improvements
in output torque, in the case of motor operation, and
significant increases in electrical output power, in
the case of generator operation.
It is a further object of the present invention
to provide the features and advantages suggested in the
aforementioned objects both in A.C. or D.C. dynamoelectric
machines.
In order to achieve the above objects, as well
as others which will become apparent hereafter, a
dynamo-electric machine in accordance with the present
invention comprises a frame, and a rotatable shaft
supported by said frame. A cylindrical rotor is mounted
coaxially on said shaft, said cylindrical rotor
defining two axial end surfaces each substantially in a
plane normal to said shaft and a cylindrical circum-
ferential surface coaxial with such shaft between saidaxial end surfaces. Said rotor is provided with a
plurality of grooves which are generally parallel to said
shaft and substantially uniformly spaced from each other
about said circumferential surface to define a
1224837
predetermined number of magnetic poles. A distributed
armature winding is provided which has axial portions
parallel to said shaft and received within said rotor
grooves and radial portions in the region of said end
surfaces and extending between substantially
diametrically opposite grooves with respect to said
shaft.
In a preferred embodim~nt, an important feature
is the provision of the first magnetic field producing
means mounted on said frame for producing a first
magnetic field in the region between said rotor axial
end surfaces in proximity to said rotor cylindrical
circumferential surface, and second magnetic fields
producing means for producing second magnetic field
axially beyond at least one of said axial end surfaces
to enhance the magnetic induction into said rotor,
whereby the total induction of magnetic flux into said
rotor is substantially the additive result of both said
first and second magnetic fields.
The present invention seeks to optimize the
efficiency of electric machines which utilize
distributed armature windings without materially
altering the construction, the size or the cost of such
machines. The features of the present invention can
readily be incorporated into existing more conventional
designs to significantly increase the efficiency of
such machines without sacrificing any of the features
or advantages of those machines.
~.
lZ24837
-- 8 --
Brief Descriptio~ of the D~awings
The objects and advantages of the present
invention will become apparent to those skilled in the
art when the following description of several illustrative
embodiments of the invention is read in conjunction with
the accompanying drawings, in which:
FIG. 1 is a perspective, partially exploded view
of a dynamoelectric machine in accordance with the present
invention;
FIG. 2 is an enlarged cross-sectional view of the
assembled machine shown in FIG. 1, taken along line 2-2;
FIG. 3 is a cross-sectional view of the machine
shown in FIG. 2, taken along line 3-3;
FIG. 4 is an exploded view, in perspective, of
another embodiment of a dynamoelectric machine in ac-
cordance with the present invention;
FIG. 5 is an enlarged cross-sectional view of
the assembled machine shown in FIG. 4, taken along lines
5-5;
FIG. 6 is a partial, cross-sectional view of the
machine shown in FIG. 5, taken along line 6-6;
FIG. 7 is a perspective view of half of a stator
constructed :in accordance with still another embodiment of
the present :invention.
FIG. 8 is a cross-sectional view of the stator
shown in FIG. 7, taken along line 8-8;
FIG. 9 is a partial, cross-sectional view of the
stator shown in FIG. 8, taken along line 9-9;
FIG. 10 is a cross-sectional view of a dynamo-
electric machine fully assembled and making use of stators
of the type shown in FIGS. 7-9;
FI&. 11 is an exploded view, in perspective, of
yet another embodiment of the present invention;
.. . . .. . .. . . . . . . .. .. .
l~ZA837
FIG. 12 is an enlarged, cross-sectional view of
an assembled machine of the type shown in FIG. 11;
FIG. 13 illustrates, in perspective, a stator in
accordance with a still further embodiment of the present
invention, wherein the stators are a modification of the
stators illustrated in FIGS. 11 and 12;
FIG. 14 is an enlaxged, cross-sectional view of
the stator shown in FIG. 13, taken at a cutting plane which
is normal to the axis of the stator;
FIG. 15 is an exploded view, in perspective, of
yet a further embodiment of the present invention;
FIG. 16 is an enlarged, cross-sectional view of
the machine shown in FIG. 15, taken at a cutting plane
which is essentially parallel to the axis of the machines;
FIG. 16a is a perspective view of the assembled
machine shown in FIGS. 15 and 16;
FIG. 17 is similar to FIG. 15, but shows yet an
additional embodiment in accordance with the present
invention;
FIG. 18 is similar to FIG. 16 but illustrates a
cross-sectional view of the e.nbodiment shown in FIG. 17.
FIG. 1') is a fragmented perspective view of a rot~r
construction in accordance with the present invention
which utiliz:es radially outwardly extending magnetic
portions at an axial end surface of the rotor;
FIG. 20 is an enlarged side elevational view of
the rotor shown in FIG. 19, and also showing placement
of stator magnets for cooperation with the magnetic
portions, and also showing in dashed outline an optional
configuration having extended magnetic portions and
complementary-sized end stator magnets.
FIG. 21 is similar to FIG. 19, but showing a
modified embodiment wherein the magnetic portions are
axially offset from the rotor;
FIG. 22 is similar to FIG. 20, but showing the
construction shown in FIG. 21;
1224837
-- 10 --
FIG. 23 is similar to FIG. 21, but showing a
further embodiment wherein the magnetic portions project
radially inwardly instead of radially outwardly;
FIG. 24 is similar to FIG. 22, but showing
the construction of FIG. 23;
FIG. 25 is a perspective view of still another
rotor construction in accordance with the present
invention wherein electrical conductors form a modified
squirrel cage arrangement wherein end rotor portions
serve as magnetic portions which couple the axi21
magnetic fields to the armature;
and
FIG. 26 is an enlarged cross-sectional view of the
rotor shown in FIG. 25, taken along line 26-26.
FIG. 27 is a fragmented perspective view of a
rotor in accordance with a modified embodiment of the
invention; and
FIG. 28 is an enlarged side elevational view
of the rotor shown in FIG. 27.
122483
- lOa. -
Description of the Preferred Embodiments
Referring now more specifically to the figures,
in which identical or similar parts are designated by the
same reference n~merals throughout, and first referring to
Figs. 1-3, there is shown a first presently preferred
embodiment which utilizes permanent magnets in the stators.
The permanent magnet embodiment of the dynamo-
electric machine in accordance with the present invention is
generally designated by the reference numeral 10. The ma-
chine 10 includes a generally cylindrical frame 12 of thetype normally used in conventional cylindrical rotor dynamo-
electric machines having distributed armature windings.
A shaft 14 is provided which is rotatably mounted
on the frame 12 by conventional means, such as suitable
bearings (not shown).
A cylindrical rotor or armature generally indi-
- cated by the reference numeral 16 is mounted coaxially onthe shaft 14. The cylindrical rotor 16 defines a cylin-
drical circumferential surface 16a coaxial with the shaft,
and two axial end surfaces 16b and 16c each substantially
in a plane normal to the shaft 14 and disposed at each
axial end of the cylindrical circumferential surface 16a.
The rotor or armature 16 is provided with a plurality of
rotor coil winding-receiving grooves or slots 16d which
are generally parallel to the shaft 14 and substantially
1224837
uniformly spaced from each other about the circumferential
surface 16a.
A distributed armature winding generally
indicated by the reference numeral 18 is provided on the
rotor or armature 16 in a conventional manner and having
axial portions 18a which are parallel to the shaft 14 and
received within the rotor grooves or slots 16d. The dis-
tributed armature winding also defines radial portions 18b
in the region of the end surfaces 16b and 16c which extend
between substantially diametrically opposite grooves 16d
with respect to the shaft 14. The radial portions 18b are
sometimes referred to as front winding connecting portions,
while the radial portions 18c are sometimes referred to as
back winding connecting portions.
What has been described up to this point is a
dynamoelectric machine, either a motor or generator, which
is conventional in construction.
In order to better appreciate the present
invention, a brief description of conventional dynamo-
electric machines will now be given in relation to thestructure which has been described up to this point.
According to the present state of the art, the magnetic
influence of the magnetic field established by a stator
magnetic circu:it construction interacts primarily with the
perimeter or peripheral surface 16a of the armature in
order to create torque or the force which produces rotation.
Typically, the field assembly stators are constructed with
diametrically opposite north and south magnetic pole
surfaces conforming to armature perimeter or peripheral
surface and interacts only with the axial winding portions
18a which lie in the peripheral grooves or slots 16d. Such
a conventional approach has been taken notwithstanding the
fact that the front connecting or radial portions 18b and
the back connecting or radial portions 18c have necessarily
existed in all rotor or armature windings substantially as
suggested in the figures. Yet, there has not been any
attempt to take advantage of these additional winding
i22483~
-12-
portions, at each axial surface of the rotor or armature,
in order to enhance the efficiency of the machine.
Generally, the present invention has for its
primary object to construct field assembly stators which
interact with the armature coils not only along the peri-
phery or circumferential surface of the armature or rotor,
but also along both axial sides of the armature. While
the description of various preferred embodiments that
follow disclose stator constructions which incorporate
both permanent magnet, electromagnetic, or combinations
of both, all constructions achieve the beneficial result
that additional stator magnetic fields are produced and
arranged to interact with the hitherto neglected front
and back connecting portions 18b and 18c as will be more
fully described hereafter.
Additionally, all armatures 16 are shown to be
12-coil assemblies. ~owever, this is only for illus-
trative purposes, and, as will be more fully evident from
the disclosure that follows, any armature coil assembly
can be used while still achieving the objects of the
present invention. The associated 12-segment commutator
assembly, which will be used with the 12-coil windings
shown, would normally be common to all embodiments. How-
ever, the commutator assembly has been omitted from the
illustrations in the interest of expediency and clarity
since they are fully conventional. Motor housings,
insulation and terminal wiring arrangements have likewise
been excluded for the same reason. Where shown, the
letters "N" and "S" denote north and south poles respect-
ively and are included for purposes of illustration only.Clearly, the poles can be reversed in most instances
without any adverse effects on the operation or efficiency
of the machines.
Accordingly, with each of the embodiments to be
described, there is provided magnetic field producing
means mounted on the frame 12 for producing a first
magnetic field which bridges the radial air gap between
~ZZ483~
- 13 -
the frame 12 and the cylindrieal circumferential surface
16a which is direeted to interaet with the winding axial
portions 18a, and seeond magnetic fields, in the region of
each axial end surfaee 16b, 16c of the rotor or armature
16, which are directed to interaet with the respeetive
winding eonneetion or radial-portions 18b, 18c.
Referring again to Figs. 1-3, the stator magnetic
eireuit is shown to comprise a series of permanent magnets
having the relative polarities as shown. Thus, there is
provided diametrically opposed permanent magnets 20 and 21,
of opposite polarities. The magnetic field created between
the permanent magnets 20 and 21 bridges the radial air gap
and interaets with the axial winding portions 18a of the
armature winding.
The frame 12, as shown partieularly in Figs. 1
and 2, also includes stator end portions, covers or plates
12b which close the respeetive openings formed at eaeh
axial end of the eylindrical portion 12a of the frame 12.
While one of the covers or plates 12b may be integrally
formed with the eylindrieal frame portion 12a, the other
eoyer 12b must, of eourse, be necessarily removable to
allow insertion of the rotor or armature 16 into the
frame 12.
Mounted on one frame end cover 12b, on diametri-
cally opposite sides of the shaft 14, are permanent magnets22 and 23 of opposite polarity as shown. Similarly,
permanent magnets 24 and 25, also of opposite polarity, are
disposed on diametrieally opposite sides of the shaft 14
on the other of the end frame eovers 12b. As should be
evident, providing permanent magnets of opposite polarities
on diametrieally opposite sides of the shaft 14 on each of
the frame covers 12b creates a magnetic field which couples
to the front and bae~ eonneetion or radial portions 18b and
18c to thereby interaet therewith. The maehine allows for
a signifieant improvement in efficiency over the eonven-
tional perimeter-only stator embodim~nts. Sinee the
lZ24837
- 14 -
embodiment of Figs. 1-3, as well as the other embodiments
to be described hereafter, permits interaction with a
previously untapped energy field, i.e. the axial sides of
the armature coils, the machine, when operating in a motor
mode, will function to produce a given amount of tor~ue at
the shaft utilizing only a small fraction of the normally
required current or input electrical power. Stated other-
wise, for the same amount of input electrical power, a
machine operating as a motor and incorporating the subject
invention will produce significantly more output torque at
the shaft 14. Corresponding efficiencies would, of course,
result if the machine were to be used in a generator mode.
In order to take full advantage of this addi-
tional source of interaction between the armature or rotor
and the stator fields and, therefore, to optimize upon the
efficiency which may be obtained thereby, the configuration
of the stator field is modified, where appropriate, to
enhance coupling between the stator field and the connection
or radial portions 18b, 18c of the armature winding. Thus,
it will be noted that the winding radial portions 18b and
18c at each axial end surface 16b, 16c of the rotor 16
create a build-up of overlapping windings which is minimum
at the circumferential surface 16a and gradually increases
to a maximum in the region of the shaft 14. This build-up
which is generally designated, for example, in Fig. 2 by
the reference 26, defines a generally conical convex
surface. In order to minimize the air gap between the
winding radial portions and the permanent magnets 22-25,
and therefore enhance the coupling between the stator
field in those regions with the side or connection windings,
the frame end covers 12b are configurated to generally
conform to the conical convex surfaces. Of course, as
suggested previously, the same is true for the radially
spaced magnets 20 and 21 disposed on the cylindrical
portion 12a of the frame. By minimizing the air gaps
between the permanent magnets and the associated armature
lZ24837
- 15 -
winding portions, coupling between the associated fields
are optimized and magnetic interaction, whether it is to
produce a torque or to generate an induced EMF, is enhanced.
In the embodiment of Figs. 1-3, the end covers 12b are each
shown to define a generally concave surface which conforms
to each conical convex surface defined by the radial
winding portions. Therefore, in the embodiment being
described, the first stator field is produced by the
permanent magnets 20 and 21 while the second magnetic
fields, which are produced as the result of the use of the
constructions in accordance with the present invention, are
created by the permanent magnets 22 and 23, at one axial
end, and the permanent magnets 24 and 25 at the other axial
end.
It has been found that the inclusion of the
additional permanent magnets 22-25 can more than double the
torque output from the machine without an increase in the
current requirement for the armature coils. Additionally,
a much greater EMF could be induced thereby. The mag-
nitudes of the aforementioned improvements results are
equally applicable to all of the electromagnetic config-
urations which will be described below.
It should also be pointed out with respect to the
embodiment of Figs. 1-3 that while all the stator fields in
this embodiment are produced by permanent magnets, the
same or similar results can be obtained where at least one
of these permanent magnets is replaced by an appropriate
electromagnet which displays or exhibits the same
polarities. Therefore, in the embodiment of Figs. 1-3,
at least one of the permanent magnets shown can be replaced
by an electromagnet, so that all of the stator field
producin~ means will be either permanent magnets, electro-
magnets or combinations thereof.
Referring to Figs. 4-6, there is shown another
presently preferred embodiment of the present invention
which is in the nature of a single stator embodiment
designed to use only two coils in the stator creating only
.. , ~ . ~ . . .. . . . . .. . . ..
1224837
- 16 -
one north and one south pole. The second embodiment is
generally designated by the reference numeral 30. The
armature 16 is identical to the one previously described
in connection with the first embodiment of Figs. 1-3. Here,
however, the magnetic field producing means includes two
opposing generally U-shaped magnetic cup members 32 dis-
posed in diametrically opposite sides of the rotor 16 to
substantially surround the same. Each cup member 32 has
a longitudinal portion 32a generally conforming to the
shape of the rotor circumferential portion 16a and
transverse portions 32b and 32c, respectively at each end
of the longitudinal portion 32a. Each transverse portion
32b, 32c extends from the associated longitudinal portion
32a to the region of the shaft 14, the corresponding trans-
verse portions on the opposing cup members forming air gapstherebetween proximate to the winding axial or connection
portions 18b, 18c. A stator winding 34 is provided which
extends about each cup member 32 and disposed between the
radially outermost and innermost surfaces thereof as
shown. Advantageously, each cup member winding 34 extends
about a respective longitudinal portion 32a and is
generally parallel to the shaft 14.
Circular recesses 32d are provided in each
transverse portion as shown dimensioned to receive the
shaft 14 whil~e establishing an air gap between opposing
transverse portions on each side of the shaft.
The relative polarities of the U-shaped magnetic
cup members are shown in Figs. 4 and 5. As will be clear,
there will be a magnetic field created across the air gap
at each pair of opposing poles at diametrically opposite
sides of the shaft, that magnetic field being in a position
to couple again to the connection or radial portions 18b,
18c of the armature winding. Again, therefore, coupling
with such hitherto unused armature winding portions is
provided to thereby enhance the overall efficiency and
operation of the machine.
As with the first described embodiment, the cup
members 32 are advantageously provided with surfaces 32e
, . . , . , , . . ~ . . . .. . . .. . .. . . .
i2X4837
- 17 -
and 32f which are somewhat conical in shape and which
conform as closely as practical with the generally convex
surface of the build-up 26 at each axial end of the arma-
ture. As previously suggested, such conformance of the
stator magnetic producing field elements minimize the air
gaps in the axial or end regions, optimize coupling and,
therefore, optimize interaction and output.
Because the embodiment shown in Figs. 4-6
provides the U-shaped magnetic cup members 32 which
completely surround the armature to interact with the
armature coils on all surfaces as described, the embodiment
is considered to be preferred since it will provide the
most torque power proportionate to its current requirements.
In this design, theprimary interaction thrust for motor
action (or inductive thrust for generator action) occurs
at the perimeter portions of the armature coils, which
are parallel to the stator coils, as with conventional
machines. However, secondary thrust or inductive efficiency
occurs at the axial side portions of the armature coils.
Both actions are simultaneous and combine to apply greater
magnetic force to the armature coils for either motor or
generator action, as applicable.
Still referring to Figs. 4-6, the cup members 32
are shown to be formed of stacked laminations disposed in
planes parallel to the shaft 14 and held together, for
example, with rivets 36. However, any other conventional
means for connecting the stacked laminations may be used.
In order to optimize the magnetic fields at the
axial air gaps formed between adjacent and opposing
transverse portions 32b, there is advantageously provided
a cylindrical yoke 38 which is coaxial with the shaft 14
and encloses the cup members 32 while magnetically
connecting the radially outermost surfaces of the longi-
tudinal portions 32a of the cup members 32. As is best
seen in Fig. 5, the use of such magnetic yoke 38, by
magnetically shorting the outermost poles, which do not
enter into the production of useful magnetic flux,
.. . . . . . . .. .. .
1224837
- 18 -
reduces the reluctance of the magnetic circuit in such a
way as to enhance or increase the magnetic flux available
in the various air gaps, including the radial air gaps
between the longitudinal portion 32a and the cylindrical
circumferential surface 16a of the rotor, as well as
in the axial air gaps produced in the regions of the
shaft proximate to the connection or radial winding
portions 18b, 18c of the armature. In a practical
embodiment, the yoke 38 may be joined or connected to
the U-shaped magnetic cup members in any conventional
manner such as, for example, spot welds 40 which are
suggested in Fig.- 5.
~ hile the cup members shown in Figs. 4-6 are
formed of stacked laminations disposed in planes parallel
to the shaft, the yoke 38 is, for practical reasons,
shown being formed of stacked laminations disposed in
planes normal to the shaft 14.
A modified version of the embodiment shown in
Figs. 4-6 is shown in Figs. 7-10 and the stator of this
modified embocliment is generally identified by the
reference numeral 50. Here, the windings 34 extend along
the outer peripheral surfaces 52 of the transverse
portions 32b in a plane normal to the shaft 14, in
addition to extending along the longitudinal portion as
with the embocliment shown in Figs. 4-6. In order to
maintain the winding 34 in the configuration shown and
in association with the magnetic cup member, there are
advantageously provided winding retainers 54 which are
in the nature of channels having a U-shaped cross-
sectional configuration. The middle retainer on eachtransverse portion 32b is provided with a cut-out 32d
for receiving the shaft as previously described.
Referring to Fig. 10, there is shown an electro-
dynamic machine incorporating two yokes 50 of the type
shown in Figs. 7 and 8, and the relative polarities of
the U-shaped magnetic cup members when currents are
caused to flow in the windings 34. In order to optimi2e
. . .
,,, . . .. . , . ., . . , .. ~ .. ... .... .. ... . .. .. . . ..
12Z4837
-- 19 --
the useful flux in the machine, yokes 58 are advantageously
used at each axial end of the machine to magnetically
connect the axially outermost surfaces of the transverse
portions, in addition to the cylindrical yoke 38 which
is coaxial with the shaft 14 and encloses the cup members
while magnetically connecting the radially outermost
surfaces of the longitudinal portions as described in
connection with Figs. 4 and 5. While the magnetic yokes
38 and 58 are advantageously used simultaneously as
shown in Fig. 10, it is possible to eliminate one of
these yokes with attendant decreases in improved results.
~ Jhile the cup members shown in Figs. 7-10 and
yokes 58 are formed of laminations disposed in planes
parallel to the shaft 14, the laminations of the yoke 38
are, as previously suggested, concentric with the axis
of the shaft 14.
It is possible, in connection with the stators 50
of Figs. 7-10 to enhance the useful magnetic flux in the
radial as well as axial air gaps by adding permanent
magnets and, thereby, effectively form compound magnets.
Referring to Fig. 8, there is shown, by way of example
only, the addition of permanent magnets 56 having
relative polarities as shown, these enhancing the useful
stator magnetic fields by compounding the fields created
by the electromagnets formed by the use of the windings
34. Such permanent magnets 56, therefore, are arranged
on the axially outermost surfaces of the transverse
portions 32b and are arranged to enhance the second
magnetic fields which couple with the connection or
radial portions 18b and 18c of the armature.
As with the previously discussed embodiments, the
internal surfaces of the stators 50 which face or are
disposed prsximate to the armature are configurated to
minimize the air gaps therebetween and therefore optimize
magnetic coupling. The conforming of the shape of the
stator to the convex shape of the armature windings ~s
illustrated in Fig. 9, wherein the internal surface 32e
.. . .. ... . ..
~2248:~7
- 20 -
is in the nature of a conical concave surface which is
configurated to complement the external or convex shape
of the armature end windings 18b, 18c.
Referring to Figs. 11 and 12, there is shown a
S further embodiment of the present invention which is
generally designated by the reference numeral 60. As
before, the rotor or armature is substantially the same
as previously described. In this embodiment, however,
the stator magnetie field produeing means includes two
members which may be semicireular, magnetie sectors 62
at each axial end of the rotor 16, arranged to form a
diametrical air gap 64 proximate to the winding radial
portions 18b! 18e. Eaeh seetor 62 has associated
therewith a semi-eylindrieal pxojection 66 dimensioned
to eover in elose proximity a portion of the rotor
circumferential surfaee 16a. The semi-cylindrical
projections 66 on associated sectors 62 also form
longitudinal air gaps 68 which are parallel to the shaft
14 and proximate to the winding axial portions 18a. A
winding 70 is provided which extends about the peri-
pheries of l_he sectors 62 in a plane substantially
normal to the shaft 14. In this manner, the windings 70
create a field at the diametrical air gaps 64 suitable
for eoupling to the radial winding or connection portions
18b, 18e and at the longitudinal air gaps 68 for coupling
to the axial winding portions 18a.
The relative polarities for an illustrative
arrangement and direetions of winding eurrents are
illustrated in Fig. 12. In order to enhance the useful
magnetie stator flux, there are advantageously provided
yokes, sueh as 72 whieh are in the nature of a circular
disc magnetieally connecting the axially outermost
surfaces of the magnetic seetors 62.
While the sectors 62 are shown formed of eoncentrie
laminations coaxial with the shaft 14 and slotted to
provide the diametrical air gaps 64, the sector 62 may
also be formed of a continuous spiral lamination slotted
1224837
- 21 -
to provide the diametrical air gaps. The concentric and
spiral lamination approaches each have their own advan-
tages and disadvantages insofar as connection, manu-
facturing economies, etc., and one may prove to be more
advantageous than the other in a given application.
Compounding of magnets is also possible with the
embodiment shown in Figs. 11 and 12. By way of example,
permanent magnets 74 are shown arranged on the radially
outermost surfaces of the semi-cylindrical projections
66 to enhance the useful stator magnetic fields. Whether
the additional permanent magnets 74 are used or not, it
is advantageous to make use of the yoke 72 which, as
described, is in the nature of a circular disc magneti-
cally connecting the axially outermost surfaces of the
lS magnetic sectors 62. However, because of the relative
polarities of the magnets, it is not useful to make use
of a cylindrical type yoke of the type described in
connection with, for example, Figs. 4 and 10, and which
were identified~ gy the reference numeral 38.
A modified version of the electrodynamic machine
shown in F.igs. 11 and 12 is illustrated in Figs. 13 and
14. Here, as with the embodiment shown, for example,
in Fig. 7, the modified embodiment, which is generally
designated by the reference numeral 80, provides for
each winding 70 to extend about a sector 62 and also
extend along the periphery of the radially outer surface
of an associated extension 66 as shown in Fig. 13. The
windings 70 in Fig. 13, therefore, include portions
extending along the diametrical air gaps 64 as best
shown in Fig. 14, axial portions 70a extending along the
outer surface of an associated extension 66 in a
direction parallel to the shaft 14, and a circumferential
winding portion 70b which extends along the circum-
ferential outer surface of an associated extension 66 in
a plane substantially perpendicular to the shaft 14.
With this modified embodiment 80, as best shown in Fig.
14, there is advantageously provided a cylindrical yoke
12ZA837
- 22 -
38 coaxial with the shaft 14 and magnetically connected
with the radially outermost surfaces of the semi-
cylindrical projections 66.
In accordance with another feature of the
embodiment shown in Figs. 13 and 14, the yoke which is
in the nature of the circular disc 72 may be magnetically
connected to the axially outermost surfaces of the
magnetic sector 62, so that where the cylindrical yoke 38
is used, the circular disc and cylindrical yokes are
joined together to form a continuous yoke which encloses
the respective set of sectors and associated projections.
The embodiments described above and shown in
Figs. 11-14, 16 and 18 can be described as having dual disc
stators designed to use a total of 4 stator coils, each
set of stator poles being created by two coils. As with
the other embodiments previously described, each stator
disc surrounds the armature 16 and permits interaction
with the armature coils at all surface portions thereof,
including the circumferential and end surfaces. These
designs provide greater torque power than the single stator
embodiment illustrated in Figs. 4-10. In the embodiments
of Figs. 11-14, 17 and 18, the interaction between the
stator fields and the armature windings, whether it be to
create a thrust or torque or induce a voltage in these
windings, are reversed. The main thrust occurs at the
axial side portion of the armature coils parallel to the
stator poles while the secondary thrust or inductive
interaction is at the perimeter pole extensions parallel
to the perimeter portion of the armature coils. Again,
both actions are simultaneous and combine to apply greater
magnetic force on the armature coils for motor or generator
action, as applicable.
Still referring to Figs. 11-14, 17 and 18, and
particularly Fig. 12, it should be pointed out that when
slots or diametrical air gaps 64 are formed within the
concentric or spiral laminations forming the semicircular
~ZZ4837
- 23 -
sector 62, the axially outer portions of the sectors 62,
between the windings 70 and the disc yokes 72 also
comprises, for all practical purposes, a yo~e for linkage
of both poles. Accordingly, the disc yo~es 72 are, in
effect, supplemental yo~es which assist in linking the
poles, for example the south poles at the top of Fig. 12
and the north poles at the bottom of Fig. 12.
As with the other embodiments, concave inner
surfaces 62b and 66b are provided for the same reasons
set forth with regard to the other embodiments.
Compounding of magnets is possible here too by
providing magnets 74 having relative polarities as shown
in Fig. 12.
Any conventional means may be used to join the
concentric laminations forming the semicircular sectors
62, rivets 76 being shown as one possible way of accom-
plishing this.
A triple stator electromagnetic embodiment is
shown in Figs. 15 and 16 and generally designated by the
reference numeral 90. As with the last mentioned embodi-
ment, the machine 90 comprises two semicircular magnetic
sectors 62 at each axial end of the rotor 16, and a
winding 70 extending about the peripheries of the sectors
62 in a plane substantially normal to the shaft 14 and
forming a diametric air gap 64 proximate to the winding
radial portions 18b, 18c. A cylindrical magnetic member
92 is provided which is generally coaxial with the shaft
14 and encloses the rotor 16 circumferential surface 16a.
The magnetic member 92 has pole sections 94, 96 projecting
radially inwardly into proximity to the rotor 16 circum-
ferential surface 16a. Windings 98 are provided which
extend about each of the pole sections 94, 96 as shown.
The machine 90, therefore, employs one conventional
two-pole stator positioned at the perimeter surface of the
armature and dual two-po:Le disc stators previously
described in connection with embodiments 11 and 12.
Accordingly, the arrangement of the machine 90 provide a
1224837
- 24 -
total of 6 stator coils, two of these coils each producing
one of the stator fields. Again, as with the other
embodiments, the three stators surround the armature to
permit interaction with the armature coils on all surfaces.
This design will provide the greatest torque power (or
voltage induction for generator action). In this embodi-
ment, all three stators simultaneously interact with all
armature coil surfaces and combine to produce the greatest
amount of torque. It may be additionally noted in
connection with this embodiment that when used with D.C.
current only, it will permit combination use of permanent
and electromagnets, i.e. perimeter electromagnets and axial
side or end permanent magnets, or vice versa.
The disc stators shown in Figs. 15, 16 and 16a
may be constructed in the same manner as previously
described for the dual stator embodiment except, of course,
for the provision of the pole extensions 66. Concave inner
surfaces on the semicircular sectors are provided for the
same reasons previously described. These stators can also
be constructed of one continuous band coil to create a
laminated core of desired diameter, as previously
suggested. A properly sized hole may be drilled through
the center close to the inner surface to accommodate the
size and specified number of turns of wire. A slot is
then cut along the length of the drilled hole to form the
poles and permit insertion of the coils. The back or
outer side remains whole and uncut and comprises a yoke
for linkage of both outer poles as discussed in connection
with Fig. 12.
While most dynamoelectric machines which are
provided with cylindrical rotors and distributed armature
windings on said rotors will almost of necessity result
in a build-up of overlapping windings at the axial end
surfaces of the rotor, Figs. 17 and 18 illustrate a
modification of all of the previous embodiments which
seek to compensate for that build-up 26 in a manner
122483~
- 25 -
other than providing complementary concave surfaces on
the facing stator surfaces. In the last embodiment to
be described, which is generally identified by the
reference numeral 100 in Figs. 17 and 18, the winding
radial portions 18b and 18c at each axial end surface of
the rotor 16 create a build-up 26 of overlapping windings
as previousl discussed. However, while such build-up
generally defines a conical convex surface, the modified
embodiment 100 includes magnetic projections 102
extending axially from each end surface 16b and 16c of
the rotor 16 as shown. The axial projections 102 are
configurated to extend beyond the axially outermost
points of the build-ups 26 and form protective slots 104
for the winding radial portions 18b, 18c and further
form a substantially flat surface 106 at each axial end
of the rotor 16. In this manner, the rotor 16 can be
received within a frame 12 having a cylindrical cavity
108, the radial as well as axial air gaps now being
capable of being minimized without danger of damage to
the winding radial portions 18b, 18c.
The construction of the projections 102 is not
critical as long as these projections are made of a
magnetic material. Thus, as shown in Fig. 17 and the
top of Fig. 18, the rotor 16 and the projections 102a
may be formed of stacked laminations disposed in planes
normal to the shaft. However, as suggested at the
bottom of Fig. 18, the rotor 16 may be formed of stacked
laminations disposed in planes normal to the shaft 14,
while the projections 102b are formed of stac~ed concen-
tric laminations which are coaxial with the shaft 14 orspiral. The two different constructions have varying
degrees of advantage, and the one used most be selected
on the basis of the application intended. What should
be pointed out is that the addition of the projections
102 essentially decrease the reluctance at the axial air
gaps, therefore enhancing the field in those air gaps.
The use of such additional metal to surround the build-up
12248~7
- 26 -
26 results in increased coupling to such connection or
radial portions 18b, 18c with increased efficinecy of
the overall machine.
While the machine 100 shown in FIGS. 17 and 18,
using the modified rotor described, has been shown used
with the semicircular sectors 62 and semi-cylindrical
projections 66 of the type shown in FIGS. 11 and 12 it
should be clear that this modified rotor can be used in
connection with any of the aforemetnioned embodiments in
which case the end stators need not be provided with the
modified complemental concave surfaces shown in the
various figures. Whichever the embodiment used, once
the modified rotor of FIGS. 17 and 18 is used, the stator
can be configurated to provide a perfectly cylindrical
cavity in which the various operating air gaps can be
minimized without danger of damage to the armature
windings.
While all of the aforementioned embodiments shown in
FIGS. 1-18 have been for a construction for increasing
the inductance and the coupling of lateral or end
- magnetic fields with the armature, FIGS. 19-26 illustrate
an approach which is intended to accomplish the same or
similar function but in a more efficient manner. In
FIGS. 1-18, the side or axial end stators are designed and
disposed to cooperate with the end or axial rotor winding
portions. In the embodiments of FIGS. 19-26, a more dir-
ect and more efficient approach is used for coupling or
inducing the side or end stator magnetic field with the
armature. Referring first of FIGS. 19 and 20, a
modified rotor construction in accordance with the
present invention is designated by the reference numeral
110. As described previously, the rotor 16 is provided
with angularly spaced axial grooves 16d which define
poles 112. A disc 114, made of a magnetic material,
is affixed to an axial end surface of the rotor 16
~2Z483~
- 27 -
and provided with radial slots angularly spaced about
the axis of the rotor. The slots 116 are aligned
with the grooves 16d to define magnetic portions
118, each forming an integral part of its associated
pole 112 of the rotor 16. The diameter of the disc 114
is greater than the diameter of the rotor 16 so that the
magnetic portions 118 are shown to extend radially out-
wardly from the rotor. Magnetic portions for purposes
of this application are intended to include all such
portions or extensions which are made of a magnetizable
material, such as ferrous metals. The disc 114 and,
therefore, the magnetic portions 118 are connected and
form part of the magnetic circuit of the rotor 16. Thus,
the disc 114 will normally comprise the end rotor
lamination. It is also possible, however, to attach
separate magnetic portions 118 to the rotor structure
and achieve the same or similar results.
This configuration 110 is designed primarily for
coupling of radial sections of armature coil circuits to
separate conforming end stator magnetic fields, either
concave or ring, in permanent magnet stator machines.
However, it also possesses an additional advantage
in that it can still permit a moderate degree of
lateral ar~ature coupling to existing stator magnetic
fields without the use of separate end stators. This
phenonomen is achieved in the following manner.
Referring to FIG. 20, a permanent magnet
periphery stator 120 is shown which exhibits a radially
innermost portion 120a which is one of polarity and a
radially outermost portion 120b which exhibits the
opposite polarity. The diameter of the disc 114 must
be such that the magnetic portions 118 only extend to
122483~7
- 28 -
overlap or be in proximate relationship with the
radially innermost polarity portion 120a. When the
magnetic portions extend beyond the point indicated,
the magnetic flux impact is to an extent neutralized
since both poles act simultaneously on the same
armature extension or magnetic portion 118. In this
embodiment additional inductance is obtained from the
interaction of the magnetic portion 118 with the sides
or axial end surfaces of the permanent magnet portion
120a. The surface of the magnet portion 120a which is
opposite the magnetic portion 118 is of the same
polarity as the surface of the periphery stator magnet
120 which interacts directly with the armature.
Also shown in FIG. 20 is a side or end permanent
magnet stator 122 which is likewise intended to act upon
the magnetic portion 118. When this armature configuration
is used to cooperate with separate conforming end stator
122, as it is primarily intended to do, as shown, the
length of the magnetic portions 118 may be increased
for optimum inductive capability, together with of
course, a comparable increase in end stator size (shown
in dashed outline). This is true nothwithstanding the
polar neutralizing effect previously mentioned since
the magnetic induction impact of the separate end
stator upon the outside magnetic portions 118 would more
than offset the induction loss at the inside thereof.
It will, therefore, be seen that by providing
the permanent magnets 122, the magnetic fields thus created
can interact with the armature coil radial portions and,
equally if not more importantly, with the magnetic
portions 118 to thereby increase the magnetic inductance
between the stator fields and the rotor or armature.
lZ24~337
- 29 -
The improved results attainable with the
construction shown in FIGS. 19 and 20, for example is
due to the positioning of magnetically permeate
materials in the form of the magnetic portions 118 in
the regions where the stator fields exist. The magnetic
portions 118 provide paths of lower magnetic reluctance,
thus directing significant portions of the stator fields
directly into the armature. Such directing of the
stator flux into the armature results in improved
inductance and operating characteristics including
significantly increasing the efficiency of the rotating
machine.
Referring to FIGS. 21 and 22, a modified rotor
is designated by the reference numeral 124. Here, the
same armature extension principle is used as that
described in connection with FIGS. 19 and 20. However,
the magnetic portions 126 each include an axially ex-
tending portion 126a and a radially extending portion 126b
which is perpendicular to the portion 126a. As with the
embodiment o* FIGS. 19 and 20, the magnetic portions
extend substantially from the circumferential surface 16a
of the rotor 16. However, in FIGS. 21 and 22, the
portions 126b which extend radially outwardly are offset
or spaced axially from the main part of the rotor by
25 the portions 126a. The embodiment shown in FIGS. 21
and 22 is sultable for use in the three stator wire
wound embodiment since the offset feature is designed to
permit unobstructed armature rotation past the coil
portions at the sides of the periphery stator poles.
Shown in dashed outline are optional portions
126c which project radially inwardly from the portions
126a. Thus, it is possible to utilize both extensions
126b and 126c to still further increase the inductive
characteristics. With respect to the use of this
armature configuration, including the optional use of
(1) only the magnetic portions 126b or (2) the combined use
~X24837
- 30 -
of 126b and 126c, the end stator magnet 122 (permanent
magnet or wire-wound) would be used to interact with
the magnetic portions 126b and 126c as applicable.
Also shown in FIG. 22 is a protective member 130
which is in the nature of a rigid protective cover
made of non-ferrous material which serves as a shield
for the stator structure 120 when the same is in the
nature of a wire-wound electromagnetic coil. Such
cover 130 insures that the side coil portions are pro-
tected from possible contact with the rotating magneticportions 126 and also permit construction of precise
clearance between the side coil portions and the
rotating extensions or portions 126.
In FIGS. 23 and 24, there is shown a configuration
of an improved rotor which is designated by the reference
numeral 132. The rotor 132 perhaps represents the most
versatile configuration and is suitable for use in
any of the aforementioned stator embodiments. ~ere, the
magnetic portions 136 include axial portions 136a
similar to the portions 126a and radially inwardly
extending portions 136b. The inwardly projecting
portions 136b may be constructed as shown at right angles
to the portions 136a or both portions may be canted or
rounded in accordance with principles previously described.
The latter configurations, would, of course, require
conforming concave side stator configurations. As will be
noted, this configuration has the added advantage of creating
a meaningful reason for widening the periphery stator poles,
with attendant increase in coil size, for increased
interaction with the lengthened armature core. This, of
course, results in even greater efficiency.
Referring now to F~GS. 25 and 26, a modified
squirrel cage armature rotor in accordance with the
present invention is shown and designated by the
reference numeral 138. here, the rotor comprises a
core composed of 3 sroups of laminations, 2 end
lZ2483~
groups of concentric cylindrical laminations 140 and
a centralgroup of circular or vertical laminations 142
as shown. The axial and radial portions of the elec-
trical conductors are in the nature of U-shaped solid
5 conductors 144 which are angularly distributed about
the rotor 138. The conductors 144 are affixed at their free
ends 144a and 144b to a common connector 140c. Each
free end is received within the respective cut-outs 140a
14Ob. In this embodiment, the end group of laminations
140 serve as the magnetic portions which cooperate
with the end or axial stator fields. Thus, the concentric
laminations 140 serve to coupl~ the end stator fields
to the armature 138.
The coil windings for the embodiments illustrated
in FIGS. 21-24, for example, can be incorporated onto
the armature or rotor assemblies prior to the final
bending and shaping of the preslotted radial portions
126a&b, 136a&b, respectively. This procedure may
be less awkward and more convenient for winding
the coils.
Any of the concepts which have been described in
this application may be used with any applicable elec-
trical rotating machine, including any motor in the
electric motor family, and also including multi-polar
constructions and regardless of the coil winding
techniques (wave winding, lap winding, etc.). The
principles of the invention can be used in connection
with both D.C. (e.g. Universal, permanent magnet, etc.)
or A.C. (e.g. Induction, squirrel cage, shaded pole, etc.)
machines. While the descriptions presented above have
been, for the most part, of D.C. machines, the principles
can be applied to A.C. machines by making appropriate
construction modifications. Thus, for example the single and
trinle stator embodiments previously described may be
lZ24837
- 32 -
conveniently used to construct and enhance the
efficiency of A.C. induction motors, particularly
the shaded pole type. Modifications that would be
required would be to combine either of the cited stator
configurations with a conventional squirrel cage rotor
or 2referably with any of the modified rotors shown in
FIGS. 19-26 inclusive. A shaded pole c-omponent (copper
strips or small coils) can be incorporated in both the
North and South pole stator fields at the periphery portion
in order to achieve self-starting.
In the embodiments shown in FIGS. 1-26,
enhancement of magnetic field induction is achieved by
a first magnetic circuit which primarily consists of a
magnetic field producing means in proximity to the
rotor cylindrical circumferential surface 16a, and a
second magnetic circuit which consists of a second
magnetic field producing means provided in proximity to
at least one of the axial end surfaces 16b. In the
embodiments described the magnetic field producing
means have either been in the form of electromagnets or
permanent magnets.
Referring to FIGS. 27 and 28, an alternate
approach is shown which provides enhancement of
magnetic field induction into the rotor over
conventional designs without the use of magnets at the
axial end surfaces of the machine. Here, a first
primary magnetic field is still produced by
circumferential or peripheral magnet 232, shown as an
electromagnet in FIG. 28. In particular, the primary
~ZZ4837
- 33 -
magnetic field is produced by that axial length or
portion of the electromagnet 232 which is disposed
between the rotor axial end surfaces 16b. Additional
magnetic flux is provided by extensions of the
electromagnet 232 beyond the rotor axial end surfaces
16b. In FIG. 28, one such portion is shown to the
right to the dashed line 240. While only one side of
the rotor (non-commutator side) is shown, the same
configuration is also, normally, to be used on the
other, commutator side of the rotor.
To take full advantage of the additional
magnetic field and to provide optimum induction of the
field into the rotor 160, the end laminations 162 are
provided with axial extensions 162a which shunt and
direct the additional magnetic fields and cause the
same to be induced into the rotor 160.
In the embodiment shown in FIGS. 27 and 28,
the axial extensions 162a have an axial dimension
substantially equal of the axial build-up of the radial
winding portions. Thus, it should be clear, the
axial length of the machine need not be axially
enlarged in order to benefit from such enhanced
induction. The specific axial dimensions of the
extended portions of the magnet 232 and of the
extensions 162a, however, are not critical. These
dimensions may be greater or less than the axial
dimension of the armature winding build-up. Also, the
extension of the magnets 232 need not be equal to the
axial length of the extensions 162a. Of course,
optimum coupling should be expected when they are made
substantially equal.
~224837
- 34 -
In order to facilitate winding of the coils
on the rotor, it may be desirable or necessary to
slightly enlarge the openings at the edges of the
extensions 162a (now shown). This, however, should not
S significantly decrease the inductive capability of the
structure.
While the invention has been described in
conjunction with a D.C. or universal type machine it
can also be used in A.C. induction machines.
While only one illustrative embodiment of the
invention has been described in detail, it should be
obvious that there are numerous variations and
modifications within the scope of the invention. The
invention is more particularly defined in the appended
claims.
